[SimplifyLibCalls] Inline calls to cabs when it's safe to do so

When unsafe algerbra is allowed calls to cabs(r) can be replaced by:

  sqrt(creal(r)*creal(r) + cimag(r)*cimag(r))

Patch by Paul Walker, thanks!

Differential Revision: https://reviews.llvm.org/D40069

llvm-svn: 320901

2 files changed, 124 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/cabs-array.ll b/llvm/test/Transforms/InstCombine/cabs-array.ll
new file mode 100644
index 00000000000..1c15dc1c545
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/cabs-array.ll
@@ -0,0 +1,65 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+define double @std_cabs([2 x double] %z) {
+; CHECK-LABEL: define double @std_cabs(
+; CHECK: tail call double @cabs(
+  %call = tail call double @cabs([2 x double] %z)
+  ret double %call
+}
+
+define float @std_cabsf([2 x float] %z) {
+; CHECK-LABEL: define float @std_cabsf(
+; CHECK: tail call float @cabsf(
+  %call = tail call float @cabsf([2 x float] %z)
+  ret float %call
+}
+
+define fp128 @std_cabsl([2 x fp128] %z) {
+; CHECK-LABEL: define fp128 @std_cabsl(
+; CHECK: tail call fp128 @cabsl(
+  %call = tail call fp128 @cabsl([2 x fp128] %z)
+  ret fp128 %call
+}
+
+define double @fast_cabs([2 x double] %z) {
+; CHECK-LABEL: define double @fast_cabs(
+; CHECK: %real = extractvalue [2 x double] %z, 0
+; CHECK: %imag = extractvalue [2 x double] %z, 1
+; CHECK: %1 = fmul fast double %real, %real
+; CHECK: %2 = fmul fast double %imag, %imag
+; CHECK: %3 = fadd fast double %1, %2
+; CHECK: %cabs = call fast double @llvm.sqrt.f64(double %3)
+; CHECK: ret double %cabs
+  %call = tail call fast double @cabs([2 x double] %z)
+  ret double %call
+}
+
+define float @fast_cabsf([2 x float] %z) {
+; CHECK-LABEL: define float @fast_cabsf(
+; CHECK: %real = extractvalue [2 x float] %z, 0
+; CHECK: %imag = extractvalue [2 x float] %z, 1
+; CHECK: %1 = fmul fast float %real, %real
+; CHECK: %2 = fmul fast float %imag, %imag
+; CHECK: %3 = fadd fast float %1, %2
+; CHECK: %cabs = call fast float @llvm.sqrt.f32(float %3)
+; CHECK: ret float %cabs
+  %call = tail call fast float @cabsf([2 x float] %z)
+  ret float %call
+}
+
+define fp128 @fast_cabsl([2 x fp128] %z) {
+; CHECK-LABEL: define fp128 @fast_cabsl(
+; CHECK: %real = extractvalue [2 x fp128] %z, 0
+; CHECK: %imag = extractvalue [2 x fp128] %z, 1
+; CHECK: %1 = fmul fast fp128 %real, %real
+; CHECK: %2 = fmul fast fp128 %imag, %imag
+; CHECK: %3 = fadd fast fp128 %1, %2
+; CHECK: %cabs = call fast fp128 @llvm.sqrt.f128(fp128 %3)
+; CHECK: ret fp128 %cabs
+  %call = tail call fast fp128 @cabsl([2 x fp128] %z)
+  ret fp128 %call
+}
+
+declare double @cabs([2 x double])
+declare float @cabsf([2 x float])
+declare fp128 @cabsl([2 x fp128])
diff --git a/llvm/test/Transforms/InstCombine/cabs-discrete.ll b/llvm/test/Transforms/InstCombine/cabs-discrete.ll
new file mode 100644
index 00000000000..405c073c194
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/cabs-discrete.ll
@@ -0,0 +1,59 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+define double @std_cabs(double %real, double %imag) {
+; CHECK-LABEL: define double @std_cabs(
+; CHECK: tail call double @cabs(
+  %call = tail call double @cabs(double %real, double %imag)
+  ret double %call
+}
+
+define float @std_cabsf(float %real, float %imag) {
+; CHECK-LABEL: define float @std_cabsf(
+; CHECK: tail call float @cabsf(
+  %call = tail call float @cabsf(float %real, float %imag)
+  ret float %call
+}
+
+define fp128 @std_cabsl(fp128 %real, fp128 %imag) {
+; CHECK-LABEL: define fp128 @std_cabsl(
+; CHECK: tail call fp128 @cabsl(
+  %call = tail call fp128 @cabsl(fp128 %real, fp128 %imag)
+  ret fp128 %call
+}
+
+define double @fast_cabs(double %real, double %imag) {
+; CHECK-LABEL: define double @fast_cabs(
+; CHECK: %1 = fmul fast double %real, %real
+; CHECK: %2 = fmul fast double %imag, %imag
+; CHECK: %3 = fadd fast double %1, %2
+; CHECK: %cabs = call fast double @llvm.sqrt.f64(double %3)
+; CHECK: ret double %cabs
+  %call = tail call fast double @cabs(double %real, double %imag)
+  ret double %call
+}
+
+define float @fast_cabsf(float %real, float %imag) {
+; CHECK-LABEL: define float @fast_cabsf(
+; CHECK: %1 = fmul fast float %real, %real
+; CHECK: %2 = fmul fast float %imag, %imag
+; CHECK: %3 = fadd fast float %1, %2
+; CHECK: %cabs = call fast float @llvm.sqrt.f32(float %3)
+; CHECK: ret float %cabs
+  %call = tail call fast float @cabsf(float %real, float %imag)
+  ret float %call
+}
+
+define fp128 @fast_cabsl(fp128 %real, fp128 %imag) {
+; CHECK-LABEL: define fp128 @fast_cabsl(
+; CHECK: %1 = fmul fast fp128 %real, %real
+; CHECK: %2 = fmul fast fp128 %imag, %imag
+; CHECK: %3 = fadd fast fp128 %1, %2
+; CHECK: %cabs = call fast fp128 @llvm.sqrt.f128(fp128 %3)
+; CHECK: ret fp128 %cabs
+  %call = tail call fast fp128 @cabsl(fp128 %real, fp128 %imag)
+  ret fp128 %call
+}
+
+declare double @cabs(double %real, double %imag)
+declare float @cabsf(float %real, float %imag)
+declare fp128 @cabsl(fp128 %real, fp128 %imag)