[InstSimplify] Missed optimization in math expression: squashing exp(log), log(exp)

Summary: This patch enables folding following expressions under -ffast-math flag: exp(log(x)) -> x, exp2(log2(x)) -> x, log(exp(x)) -> x, log2(exp2(x)) -> x

Reviewers: spatel, hfinkel, davide

Reviewed By: spatel, hfinkel, davide

Subscribers: scanon, llvm-commits

Differential Revision: https://reviews.llvm.org/D41381

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321710 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 284 insertions, 0 deletions

diff --git a/test/Transforms/InstSimplify/exp-intrinsic.ll b/test/Transforms/InstSimplify/exp-intrinsic.ll
new file mode 100644
index 00000000000..0fbd7e1a5e9
--- /dev/null
+++ b/test/Transforms/InstSimplify/exp-intrinsic.ll
@@ -0,0 +1,71 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+declare double @llvm.exp.f64(double)
+declare double @llvm.log.f64(double)
+
+define double @exp_log(double %a) {
+; CHECK-LABEL: @exp_log(
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.log.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.exp.f64(double [[TMP1]])
+; CHECK-NEXT:    ret double [[TMP2]]
+;
+  %1 = call double @llvm.log.f64(double %a)
+  %2 = call double @llvm.exp.f64(double %1)
+  ret double %2
+}
+
+define double @exp_log_fast(double %a) {
+; CHECK-LABEL: @exp_log_fast(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call fast double @llvm.log.f64(double %a)
+  %2 = call fast double @llvm.exp.f64(double %1)
+  ret double %2
+}
+
+define double @exp_fast_log_strict(double %a) {
+; CHECK-LABEL: @exp_fast_log_strict(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call double @llvm.log.f64(double %a)
+  %2 = call fast double @llvm.exp.f64(double %1)
+  ret double %2
+}
+
+define double @exp_strict_log_fast(double %a) {
+; CHECK-LABEL: @exp_strict_log_fast(
+; CHECK-NEXT:    [[TMP1:%.*]] = call fast double @llvm.log.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.exp.f64(double [[TMP1]])
+; CHECK-NEXT:    ret double [[TMP2]]
+;
+  %1 = call fast double @llvm.log.f64(double %a)
+  %2 = call double @llvm.exp.f64(double %1)
+  ret double %2
+}
+
+define double @exp_log_exp_log(double %a) {
+; CHECK-LABEL: @exp_log_exp_log(
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.log.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.exp.f64(double [[TMP1]])
+; CHECK-NEXT:    [[TMP3:%.*]] = call double @llvm.log.f64(double [[TMP2]])
+; CHECK-NEXT:    [[TMP4:%.*]] = call double @llvm.exp.f64(double [[TMP3]])
+; CHECK-NEXT:    ret double [[TMP4]]
+;
+  %1 = call double @llvm.log.f64(double %a)
+  %2 = call double @llvm.exp.f64(double %1)
+  %3 = call double @llvm.log.f64(double %2)
+  %4 = call double @llvm.exp.f64(double %3)
+  ret double %4
+}
+
+define double @exp_log_exp_log_fast(double %a) {
+; CHECK-LABEL: @exp_log_exp_log_fast(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call fast double @llvm.log.f64(double %a)
+  %2 = call fast double @llvm.exp.f64(double %1)
+  %3 = call fast double @llvm.log.f64(double %2)
+  %4 = call fast double @llvm.exp.f64(double %3)
+  ret double %4
+}
diff --git a/test/Transforms/InstSimplify/exp2-intrinsic.ll b/test/Transforms/InstSimplify/exp2-intrinsic.ll
new file mode 100644
index 00000000000..6b93b14b711
--- /dev/null
+++ b/test/Transforms/InstSimplify/exp2-intrinsic.ll
@@ -0,0 +1,71 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+declare double @llvm.exp2.f64(double)
+declare double @llvm.log2.f64(double)
+
+define double @exp2_log2(double %a) {
+; CHECK-LABEL: @exp2_log2(
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.log2.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.exp2.f64(double [[TMP1]])
+; CHECK-NEXT:    ret double [[TMP2]]
+;
+  %1 = call double @llvm.log2.f64(double %a)
+  %2 = call double @llvm.exp2.f64(double %1)
+  ret double %2
+}
+
+define double @exp2_log2_fast(double %a) {
+; CHECK-LABEL: @exp2_log2_fast(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call fast double @llvm.log2.f64(double %a)
+  %2 = call fast double @llvm.exp2.f64(double %1)
+  ret double %2
+}
+
+define double @exp2_fast_log2_strict(double %a) {
+; CHECK-LABEL: @exp2_fast_log2_strict(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call double @llvm.log2.f64(double %a)
+  %2 = call fast double @llvm.exp2.f64(double %1)
+  ret double %2
+}
+
+define double @exp2_strict_log2_fast(double %a) {
+; CHECK-LABEL: @exp2_strict_log2_fast(
+; CHECK-NEXT:    [[TMP1:%.*]] = call fast double @llvm.log2.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.exp2.f64(double [[TMP1]])
+; CHECK-NEXT:    ret double [[TMP2]]
+;
+  %1 = call fast double @llvm.log2.f64(double %a)
+  %2 = call double @llvm.exp2.f64(double %1)
+  ret double %2
+}
+
+define double @exp2_log2_exp2_log2(double %a) {
+; CHECK-LABEL: @exp2_log2_exp2_log2(
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.log2.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.exp2.f64(double [[TMP1]])
+; CHECK-NEXT:    [[TMP3:%.*]] = call double @llvm.log2.f64(double [[TMP2]])
+; CHECK-NEXT:    [[TMP4:%.*]] = call double @llvm.exp2.f64(double [[TMP3]])
+; CHECK-NEXT:    ret double [[TMP4]]
+;
+  %1 = call double @llvm.log2.f64(double %a)
+  %2 = call double @llvm.exp2.f64(double %1)
+  %3 = call double @llvm.log2.f64(double %2)
+  %4 = call double @llvm.exp2.f64(double %3)
+  ret double %4
+}
+
+define double @exp2_log2_exp2_log2_fast(double %a) {
+; CHECK-LABEL: @exp2_log2_exp2_log2_fast(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call fast double @llvm.log2.f64(double %a)
+  %2 = call fast double @llvm.exp2.f64(double %1)
+  %3 = call fast double @llvm.log2.f64(double %2)
+  %4 = call fast double @llvm.exp2.f64(double %3)
+  ret double %4
+}
diff --git a/test/Transforms/InstSimplify/log-intrinsic.ll b/test/Transforms/InstSimplify/log-intrinsic.ll
new file mode 100644
index 00000000000..5d9820e20ba
--- /dev/null
+++ b/test/Transforms/InstSimplify/log-intrinsic.ll
@@ -0,0 +1,71 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+declare double @llvm.log.f64(double)
+declare double @llvm.exp.f64(double)
+
+define double @log_exp(double %a) {
+; CHECK-LABEL: @log_exp(
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.exp.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.log.f64(double [[TMP1]])
+; CHECK-NEXT:    ret double [[TMP2]]
+;
+  %1 = call double @llvm.exp.f64(double %a)
+  %2 = call double @llvm.log.f64(double %1)
+  ret double %2
+}
+
+define double @log_exp_fast(double %a) {
+; CHECK-LABEL: @log_exp_fast(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call fast double @llvm.exp.f64(double %a)
+  %2 = call fast double @llvm.log.f64(double %1)
+  ret double %2
+}
+
+define double @log_fast_exp_strict(double %a) {
+; CHECK-LABEL: @log_fast_exp_strict(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call double @llvm.exp.f64(double %a)
+  %2 = call fast double @llvm.log.f64(double %1)
+  ret double %2
+}
+
+define double @log_strict_exp_fast(double %a) {
+; CHECK-LABEL: @log_strict_exp_fast(
+; CHECK-NEXT:    [[TMP1:%.*]] = call fast double @llvm.exp.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.log.f64(double [[TMP1]])
+; CHECK-NEXT:    ret double [[TMP2]]
+;
+  %1 = call fast double @llvm.exp.f64(double %a)
+  %2 = call double @llvm.log.f64(double %1)
+  ret double %2
+}
+
+define double @log_exp_log_exp(double %a) {
+; CHECK-LABEL: @log_exp_log_exp(
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.exp.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.log.f64(double [[TMP1]])
+; CHECK-NEXT:    [[TMP3:%.*]] = call double @llvm.exp.f64(double [[TMP2]])
+; CHECK-NEXT:    [[TMP4:%.*]] = call double @llvm.log.f64(double [[TMP3]])
+; CHECK-NEXT:    ret double [[TMP4]]
+;
+  %1 = call double @llvm.exp.f64(double %a)
+  %2 = call double @llvm.log.f64(double %1)
+  %3 = call double @llvm.exp.f64(double %2)
+  %4 = call double @llvm.log.f64(double %3)
+  ret double %4
+}
+
+define double @log_exp_log_exp_fast(double %a) {
+; CHECK-LABEL: @log_exp_log_exp_fast(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call fast double @llvm.exp.f64(double %a)
+  %2 = call fast double @llvm.log.f64(double %1)
+  %3 = call fast double @llvm.exp.f64(double %2)
+  %4 = call fast double @llvm.log.f64(double %3)
+  ret double %4
+}
diff --git a/test/Transforms/InstSimplify/log2-intrinsic.ll b/test/Transforms/InstSimplify/log2-intrinsic.ll
new file mode 100644
index 00000000000..dab0cdf9797
--- /dev/null
+++ b/test/Transforms/InstSimplify/log2-intrinsic.ll
@@ -0,0 +1,71 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+declare double @llvm.log2.f64(double)
+declare double @llvm.exp2.f64(double)
+
+define double @log2_exp2(double %a) {
+; CHECK-LABEL: @log2_exp2(
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.exp2.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.log2.f64(double [[TMP1]])
+; CHECK-NEXT:    ret double [[TMP2]]
+;
+  %1 = call double @llvm.exp2.f64(double %a)
+  %2 = call double @llvm.log2.f64(double %1)
+  ret double %2
+}
+
+define double @log2_exp2_fast(double %a) {
+; CHECK-LABEL: @log2_exp2_fast(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call fast double @llvm.exp2.f64(double %a)
+  %2 = call fast double @llvm.log2.f64(double %1)
+  ret double %2
+}
+
+define double @log2_fast_exp2_strict(double %a) {
+; CHECK-LABEL: @log2_fast_exp2_strict(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call double @llvm.exp2.f64(double %a)
+  %2 = call fast double @llvm.log2.f64(double %1)
+  ret double %2
+}
+
+define double @log2_strict_exp2_fast(double %a) {
+; CHECK-LABEL: @log2_strict_exp2_fast(
+; CHECK-NEXT:    [[TMP1:%.*]] = call fast double @llvm.exp2.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.log2.f64(double [[TMP1]])
+; CHECK-NEXT:    ret double [[TMP2]]
+;
+  %1 = call fast double @llvm.exp2.f64(double %a)
+  %2 = call double @llvm.log2.f64(double %1)
+  ret double %2
+}
+
+define double @log2_exp2_log2_exp2(double %a) {
+; CHECK-LABEL: @log2_exp2_log2_exp2(
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.exp2.f64(double [[A:%.*]])
+; CHECK-NEXT:    [[TMP2:%.*]] = call double @llvm.log2.f64(double [[TMP1]])
+; CHECK-NEXT:    [[TMP3:%.*]] = call double @llvm.exp2.f64(double [[TMP2]])
+; CHECK-NEXT:    [[TMP4:%.*]] = call double @llvm.log2.f64(double [[TMP3]])
+; CHECK-NEXT:    ret double [[TMP4]]
+;
+  %1 = call double @llvm.exp2.f64(double %a)
+  %2 = call double @llvm.log2.f64(double %1)
+  %3 = call double @llvm.exp2.f64(double %2)
+  %4 = call double @llvm.log2.f64(double %3)
+  ret double %4
+}
+
+define double @log2_exp2_log2_exp2_fast(double %a) {
+; CHECK-LABEL: @log2_exp2_log2_exp2_fast(
+; CHECK-NEXT:    ret double [[A:%.*]]
+;
+  %1 = call fast double @llvm.exp2.f64(double %a)
+  %2 = call fast double @llvm.log2.f64(double %1)
+  %3 = call fast double @llvm.exp2.f64(double %2)
+  %4 = call fast double @llvm.log2.f64(double %3)
+  ret double %4
+}